POWER STEERING FAILURE

POWER STEERING FAILURE 

STIFF STEERING / STEERING WHEEL STIFF

It was a perfect sunny day  with hardly any breeze, when my wife and I decided to go for a Sunday outing. We loaded the  VW Polo 2.0L Highline, with picnic umbrella, and packed a picnic basket filled with food and refreshments.  I mounted the bicycle holder on the tow-bar ball and attached our 2 bicycles, and off we went. But our joyous mood  was  abruptly interrupted about halfway to our destination when the Polo had  a sudden steering problem.  This is probably the worst thing that can happen to any unsuspecting driver whilst driving in a relaxed state. As I was entering into a long but sharp curve, my power steering kinda "froze for a second" .  I was steering with one hand — which is all it normally takes  — because the steering wheel is so light. But before I could respond to grip the steering with two hands, I also instinctively braked and with screeching tyres, I hit the pavement so hard that both front airbags popped.

The steering wheel had suddenly become hard to turn / stiff and tight /difficult to turn.  Kinda difficult to explain.  A stiff hard to turn steering wheel as if there is no power steering.  It was light to steer when suddenly it was hard to turn the steering wheel, because the steering wheel went stiff.  A stiff steering when turning. The steering wheel becomes stiff and hard to turn. I hope you know what I mean. Fortunately there wasn't a another car involved and even more fortunate nobody got injured except my pride. The first thing that went through my mind after calming the wife down and confirming that she was ok, was to determine the extent of the damage. 

As the airbags deflated I looking at the dashboard and saw all the light on the dashboard glowing. The yellow EPC light was on, the yellow steering wheel light (K161) was on, the ABS light was on, the red battery light was on, and the yellow brake pad light was on. The engine had switched off  and I realized the ignition was still on.  So I tried started the engine and it wouldn't take, I switch the ignition off and tried again, all the light went out and the car idled. On further inspection, I saw the rim that hit the curb was deformed and the tyre was flat. I figured I could just fit the spare and we would be on our way. As I reversed away from the pavement,  the steering wheel  was back to normal, it was light again.  After fitting the spare wheel, I  turned the steering wheel two full turns in either direction with one hand or rather my fingertips.  This was very odd, even peculiar, because the Polo just came back from its 100k service / cam belt replacement a short while ago. I'm certain if there was any problem with my steering wheel my machy would have told me but he said absolutely nothing. Anyway, so we eventually get home and as I turned into my driveway the steering goes hard/stiff/difficult to turn once again. As I drove forward the steering wheel returned to normal. So I popped the bonnet, checking for anything out of the ordinary. I rolled under the Polo, checked the steering control module, looked at the steering pump (V187), yet it all checked out fine. Out came VCDS and I scanned the Polo and found the battery connection to be intermittent. Look at the 18010/P1602 error below.

Chassis Type: 9N - VW Polo
Scan: 01,02,03,08,09,15,17,19,25,37,44,45,46,56,76
---------------------------------------------------
Address 01: Engine       Labels: None
Controller: 06A 906 032 PB
Component: 2.0l ME7.5.10       0305
Coding: 00071
Shop #: WSC 01120
AAVZZZ9NZ7UXXXXX     VWZ7Z0G52XXXXX
1 Faults Found:
18010 -  Power Supply Terminal 30: Voltage too Low
P1602 - 35-10 -   - - Intermittent
Readiness: 0000 0000
---------------------------------------------------
Address 15: Airbags
Control Module Part Number: 6Q0 909 601 F
Component and/or Version: 05 AIRBAG VW5  0010
Software Coding: 12341
Work Shop Code: WSC 31414
6 Faults Found:
00595 -  Crash Data Stored
35-00 -   -
01214 - Crash Data for Belt Tensioner Stored
35-00 - -
00588 - Airbag Igniter; Driver Side (N95)
32-00 - Resistance too High
00589 - Airbag Igniter 1; Passenger Side (N131)
29-10 - Short to Ground - Intermittent
00589 - Airbag Igniter 1; Passenger Side (N131)
32-10 - Resistance too High - Intermittent
01280 -  Airbag; Passenger Side; Disabled
35-00 -   -
---------------------------------------------------

Thereafter I decided I was going to take the Polo back on the road. So I reversed out of the driveway and suddenly the problem was back. The only thing I did was climb the 30 mm coping at the edge of the driveway so I drove back into the driveway and as the  back wheels hit the driveway copping the steering was fine once more. Since the steering pump (V187) actually stops working for the second or so, it had to be something to do with the power. So I pulled on every visible cable that goes into the wiring harness to the steering pump (V187). I even checked the enclosed fuses on top of the battery when I noticed that the negative battery terminal wasn't properly tightened.  As I tightened the nut I discovered the nut was stripped and wouldn't tighten any further. Then realized this had to be the problem. I scratched around in the garage, found a screw that would work, tightened the battery terminal and reversed out of the driveway and drove it back in a few times and the problem didn't reoccur. So I called my wife and asked her move the steering wheel to and fro with her hand while standing outside the Polo with her hand  through the open window. I loosened the battery terminal and disconnected the battery while the polo was idling. When it was disconnected my wife couldn't move the steering wheel and when I replace the terminal she could. So I was totally convinced that the intermittent battery contact caused intermittent power to the pump which is exactly what happened a second before I fit the pavement.  
So now I had to track down the cowboy who stripped by battery terminal nut because the  last time I took the battery out to replace my headlight bulbs I personally tightened it and am darn sure it wasn't stripped. This was roughly a week before it went for that major service. It just had to be one of the workshop guys that was responsible so like three days later I went to my VW /Audi machy's workshop to complain and demanded compensation for the damage to my car but got the saddest news. The same Sunday that my wife and I want for our picnic my VW/Audi machy was out biking and was killed in a head-on collision and died on the spot. 

Here are some VW, Audi power steering problems listed below, all of which seem to have a (G85) sensor issue.

Address 03: ABS Brakes
Controller: 7L0 907 379 G
Component: ESP ALLRAD MK25 0203
Coding: 0006402
Shop #: WSC 3141
00778 - Steering Angle Sensor (G85)
000 - -

Address 34: Level Control
Controller: 7L0 907 553 F
Component: LUFTFDR.-CDC- 3C3P1 3081
Coding: 0015521
Shop #: WSC 02631
00778 - Steering Angle Sensor (G85)
004 - No Signal/Communication

Address 03: ABS Brakes
Part No: 6Q0 907 379 M
Component: front H02 0001 ESP 5.7
Coding: 0000000
Shop #: WSC 00000 000 00000
00778 - Steering Angle Sensor (G85) 
005 - No or Incorrect Basic Setting / Adaptation

Address 44: Steering Assist
Part No: 1K1 909 144 J
Component: EPS_ZFLS Kl.5   D04 1606
Shop #: WSC 00000 000 00000
00778 - Steering Angle Sensor (G85)
000 - -

Address 03: ABS Brakes    
Part No: 1K0 907 379 K
Component: ESP FRONT MK60      0104
Coding: 0021121
00778 - Steering Angle Sensor (G85) 
005 - No or Incorrect Basic Setting / Adaptation

Address 44: Steering Assist Labels: 6Q0-423-156.lbl
Part No: 6R0 423 156 B
Component: LenkhilfeTRW V277
Coding: 11221
Shop #: WSC 06402
00778 - Steering Angle Sensor (G85) 
49-00 - No Communications

When I surfed the net, I discovered that several other VW owners experience similar problems. Here a dude who says:- "The dealership keeps giving my car back to me unfixed yet still replacing parts! The dangerous part of this is the steering locks up when the car dies and i'ts still moving. I am fearful of driving it and I haven't gotten anywhere with VW.  I am not alone and that it seems to be the same particular year and engine as mine in most owners replies.  I would like to help find a solution before any serious accidents happen or anyone is hurt. Thanks".

The Steering Angle Sensor (G85) is an opto coupler fitted in a collar under the steering wheel airbag. It sends sends the  steering wheel position to the Power Steering Control Module (J500) at the base of the steering column interfacing with the Electro-mechanical Power Steering Motor V187 all of which need power to operate properly. If the power disappears, the pump doesn't work and the steering goes stiff until the power is restored.


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CHECK ENGINE LIGHT

CHECK ENGINE LIGHT

 VW BASHING

In my humble opinion I think VW manufactures pretty decent cars especially since  several of their models  won car of the year, a few years in a row. In fact VW Polo is probably the least troublesome VAG car and unfortunately the VW Jetta is the most troublesome. However not everyone is impressed with VW and from what goes around  at VW service departments about the flashing check engine light and especially coming from the mouths of VW owners,  borders on disgust and disappointment. Some of the things I've heard them say are:- Volkswagens Suck- and their service departments suck even more. They are an unorganized bunch of monkeys ... VW as a company - customer service is definitely not their priority. The check engine light is how they make money. The Worst customer service I have EVER received.  VW cars need no introduction but they do need constant attention. I will never buy Volkswagen again. As soon as my VW Golf gets out of the shop I'm trading it in for a Hyundai! Volkswagon cars are shit. I'm seriously interested in a "don't buy VW campaign". Never, ever buy a Volkswagen because VW service departments give Toyota cars as loaners. I really loved Jettas before, but now they SUCK. 

Volkswagen do not have an engine number, it an expire date. When I said I drive a VW, the mechanic said "what a shitty vehicle". I don't know how I will sell this disaster of a car! So don't sell it - just trade it in and get a non-VW. The time and effort to fight with corporate Volkswagen will get you no where. Their monkeys do what they are trained to do. Most VWs are lemons and the service people know it. VW quality and service is terrible - I will never buy another VW product.  VW service people are complete fools. Mostly my problems have been with idiot VW repair people, piss poor VW customer service, yep I agree a lot of service departments do suck. VW "wear and tear" - what a load of crap - more like cheaply made, more plastic than metal. The service people at VW are awful to deal with because they know VW sucks. My recent problems with bad service turned to NO service after calling VWoA. Customer service at VW sucks...they are programmed to say: "I'm sorry you are having issues with you vehicle" over and over. 

So, where does this leave avid VW fans like you and me? Do we jump on the VW bashing band wagon or do we take a stand? What I'd like to say in defence of VW, is that since the SAE mandated ODB-II for all makes of vehicles built after 1996  and even supplied a list of generic diagnostic Trouble Codes (DTCs), meaning codes relevant to all cars. Its only a matter of time before all modern day cars start misbehaving and frustrate their owners like some VWs frustrate some of their owners. Little do we know what is happening in the diagnostic and repair, misbehaving and frustration ranks of Honda, Mercedes Benz, Kia, Hyundai,  Opel, Ford, GWM, Renault, Mazda, Alfa Romeo, Bentley, Chrysler, Fiat, Nissan, Jaguar, Lexus, Jeep, Chery, Daewoo, Toyota, Mitsubishi, Peugot, Volvo, Tata, Citroen, Dodge, Proton, Suzuki, Geely, BMW, Isuzu, Porche, etc. Considering most mechanical service departments may not have the necessary electronic savvy diagnostic skilled technical personal, automotive problems are going to be on the rise and more expensive to repair than ever before because unskilled and untrained mechanics are bound to take "like forever" to find the faults by guessing and by trial and error. I personally know of a case where a car  was in for service and repair for 52 days in a single year because the "automotive technicians" could not locate the source of the trouble.

COMMON VW CHECK ENGINE LIGHT PROBLEMS

A typical problem with Jetta / Jetta GLI / Jetta GLI 2.0L T / Jetta LX 5 cyl (2010-2011) / VW  Passat, Beetle, Golf, Tiguan, Routan, Eos, GTI and the VW  Taureg is the Check Engine Light (CEL) aka (MIL-Malfunction Indicator Lamp) that flashes or blinks continually or stays on especially in cold weather which is normally caused by a faulty Check Engine Light sensor. But when the Check Engine Light  (CEL) aka (MIL- Malfunction Indicator Lamp) comes on and the whole car shudders and shakes in an almost uncontrollable manner, not only does it sound expensive but also feels expensive. Check Engine Light  (CEL) aka (MIL-Malfunction Indicator Lamp) is also associated with failure to start, noisy  cranking, backfires, stalling and shaking, rev hesitation, visible black emissions and even engine fires. These issues often flags a P300 (random misfire) which motor mechanics, sorry "automotive technicians" readily pass over as a random glitch, returning the car to the owner saying "no problem found". A glitch that is bound to reoccur whist driving on the inside lane during peak hour traffic, which could consequently leave  the driver stranded on the express way.  This supposedly random error is actually a tell tail sign uttered by one of the ignition coils ( N70, N127, N291, N292) or injectors (N30-N34). A failing Ignition Coil  or a failing Injector gives exactly the same symptoms, upto and including turning on the EPC light (Electronic Power Control), the Check Engine Light (CEL) aka (MIL-Malfunction Indicator Lamp), limits the power and sends the car into limp mode and flags the relevant Diagnostic Trouble Codes (DTCs). Injector DTCs are from P0200 to P0212 and P0261 to P0296. Whereas Ingiton coils DTCs are normally from P02300 to P02335. Unlike older cars that have one coil that could go faulty, which would stop the car in its tracks. Modern day Volkswagen cars, have one ignition coil for each spark plug, implying 4 times the possibility of failure on a 4 cylinder and 6 times  the possibility of failure on a 6 cylinder engine and more ignition coils for the spark plugs per cylinder engines.  If 1 ignition coil or 1 injector fails, the other coils continue to keeps on firing their individual spark plugs. Along with the functioning injectors  keep the engine running but unbalanced due to one cylinder not lagging behind-- because of a dead coil or injector. This shake is so bad that it makes driving the car virtually impossible.  Since, it is very unlikely that 2 coils or 2 injectors would fail at exactly the very same instant, a quick and easy repair method is to keep a new spare coil and injector in the tools box which could be replaced by the process of elimination until the problem is solved.

The other common Check Engine Light  (CEL) aka ( (MIL-Malfunction Indicator Lamp) culprit is the mass air flow (MAF) sensor (G70) which works in conjunction with the Oxygen (O2) sensor to provide the correct volume of air for  stoichiometric calculations.  The MAF is situated between the throttle body and the air filter pan and sends direct predicted air flow data to the ECU, while the oxygen sensor sends feedback data to the ECU so that it can  make the minor corrections to the predicted air mass. Mass Air Flow Sensors (G70) are mechanical devices and therefore prone to failure since their measuring elements tend to get worn overtime, flagging  P1144, P1145 or P1146 DTCs. Mass Air Flow Sensors can possibly cause a wide range of engine problems much like those caused by the ignition coils and injectors. It is therefore essential to download the Diagnostic Trouble code (DTC) memory to determine whether the ignition coils, the injectors or the Mass Air Flow Sensors is causing the problem.

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AUDI EPC LIGHT PROBLEMS

AUDI EPC LIGHT

It is common knowledge that EPC light problems have been haunting Audi drivers incessantly for the past few years, announcing itself on Audi A1,  Audi A2, Audi A3,  Audi A4,  Audi A5, Audi A6,  Audi A7,  Audi A8,  Audi Q3,  Audi Q5, Audi Q7, the Audi RS4,  Audi RS6, Audi RS8, Audi R8, Audi S4, Audi S6, Audi S8 and Audi  TTs even before they're run-in. Several Audi owners are dismayed that EPC problems present themselves on virtually new cars. 

In fact, EPC problems pop-up at any time, on any Audi new or old fitted with X-by-Wire technology. Any Audi  without a throttle cable, is naturally fitted with a full Drive-by-Wire system which is supervised by the Electronic Control Circuit (EPC)  / Electronic Throttle Control (ETC)  that turns on the dashboard mounted EPC (K132) indicator light when it detects a malfunction, then registers Diagnostic Trouble Codes (DTC)  in the ECM memory.  Even though the EPC light turns on exclusively for  non-emission related faults, it does however turn on along with the MIL for emission related faults. 

The EPC  / ETC is a torque monitoring circuit and monitors for torque discrepancies and torque inefficiencies and when it detects one, sends the vehicle into emergency running mode (limp mode). These are prevalent when towing, when driving up an incline, when in manual mode, when in cruise control, after spirited driving, etc, and may even cause the ABS, ESP   lights to came on. Some drivers, assume  that it's happening more frequently over time and others are concerned that the EPC trouble are going to get worse because of its  randomness. But this is not the case. 

Bear in mind that once the EPC light is on, no other EPC related fault is going to make it glow any brighter. Once it's on, it's stays on even if the battery is disconnected, and it will come back on when you reconnect. However, the ECU will monitor the EPC circuit and if the same error does not occur in three successive trips of at least 7 kilometers, it will erase the DTC and it would seem as if it never happened, until the next time.  These are safely features specific to Drive by Wire systems and their workings can be viewed in the adaptation groups when retrieving errors with a scan tool.

ADAPTATION GROUPS PERTAINING TO EPC

Group 60 -- Throttle Valve Adjuster / Adaptation Epc-system

Group 61 -- Epc-system / Throttle Valve Adjuster (System 1) 

Group 62 -- Epc-system / Throttle Valve Adjuster (System 2)

Group 63 -- Kickdown Function

Group 66 -- Cruise Control Status

AUDI EPC LIGHT RELATED DTC

18039 / P1631 - Accelerator Position Sensor (G79): Signal too High 

18041 / P1633 - Accelerator Position Sensor 2 (G185) Signal too Low

18042 / P1634 - Accelerator Position Sensor 2 (G185): Signal too High

18047 / P1639 - Accelerator Position Sensor 1/2 (G79/G185): Implausible Signal 

 00777 - Accelerator Position Sensor (G79): Implausible Signal

No response from the throttle even with your foot flat on the accelerator pedal.. There are two potentiometers fitted to the accelerator pedal which are monitored by the ECU and when it it detects an intermittent signal from one pot, it turns on the EPC light then uses the second pot for acceleration but it is limited. When both pots detected as are intermittent, EPC light goes on and engine only runs at idle speed. When this error occurs, turn the engine off, stomp on the accelerator a few times through its full travel.  It could just be specks of dust that settled on the one of the potentiometer (variable resistors) tracks that stymied the ECU for a few millisecond or so. I this happens often and thereafter, presenting a 18047 / P1639 or 18039 / P1631 or 18042 / P1634 or 18041 / P1633 then consider replacing the accelerator pedal.

No response from the throttle even with your foot flat on the accelerator pedal. There are also two redundant potentiometers in the throttle body that determines the throttle valve angle and it has three modes of failure. One for when the valve angle sensor fails, one for when throttle valve actuator (motor) malfunctions and one for when throttle valve position is cannot be recognized by the ECU. When this happens  the ECU shuts off the voltage supply to the actuator, causing the throttle valve to defaults to mechanical stop position and the engine speed is limited to 1200 RPM. If any of the DTC fault below show up in your scan, check the 6 pin plug interfacing with the throttle body. It would be best to redo adaptation thereafter before thinking of replacing the throttle body. 

000289 / P0121- Throttle Position Sensor (G69): Implausible Signal - Intermittent

16506 / P0122 - Throttle Position Sensor (G69): Signal too Low - Intermittent

17987 / P1579 - Throttle Actuator (J338): Adaptation Not Started - Intermittent

17976 / P1568 - Throttle Actuator (J338): Mechanical Failure 

17972 / P1564 - Throttle Actuator (J338): Under-Voltage during Basic Setting 

17952 / P1544 - Angle Sensor 1 for Throttle Actuator (G187): Signal too Large - Intermittent

16606 / P0222 - Angle Sensor 2 for Throttle (G188): Signal Too Low - Intermittent

000547 / P0223 - Angle Sensor 2 for Throttle (G188):Signal Too High - Intermittent

17581 / P1173 -  Angle Sensor 2 for Throttle Actuator (G188) Signal too High 

18042 / P1634 - Accelerator Position Sensor 2 (G185): Signal too High 

You have difficulty starting but eventually does start but idles very rough, bucks and surges when you attempt to drive it. The   EPC, MIL (Check engine light)  and ESP lights come on. This is most likely caused by the Injectors  N30-N33 or the Ignition Coils N (1st cylinder), N128 (2nd cylinder), N158 (3rd cylinder) and N163 (4th cylinder) since both the Injectors and Ignition coils causes exactly the same symptoms. It also   exhibit the following DTCs.

17633 / P1225 - Fuel Injector for Cylinder 1 (N30): Short to Ground  - - Intermittent

17634 / P1226 - Fuel Injector for Cylinder 2 (N31): Short to Ground  - - Intermittent

17635 / P1227 - Fuel Injector for Cylinder 3 (N32): Short to Ground  - - Intermittent

17636 / P1228 - Fuel Injector for Cylinder 4 (N33): Short to Ground  - - Intermittent

MORE EPC PROBLEMS

J757 Engine Component Power Supply Relay cause loss of  high-pressure and turns on EPC. ESP and MIL lights.

N75 Solenoid valve for charge pressure limitation and turns on the  EPC and MIL lights but shown no symptoms of failure except go into limp mode. 

Audi A1, Audi A2, Audi A3, Audi A4, Audi A5, Audi A6, Audi A7, Audi A8, Audi Q3, Audi Q5, Audi Q7, the Audi RS4, Audi RS6, Audi RS8, Audi R8, Audi S4, Audi S6, Audi S8 and Audi  TTs EPC Problems.

LIMP MODE

LIMP MODE HOME / VW LIMP MODE

What is "limp mode", has been "The Question" of  2013-2014.  Limp mode is a design feature of all drive by wire systems. Vag cars fitted with ME 7.0 or newer are all fitted with electronic drive-by-wire systems in place the fast aging and outmoded cable throttle system.  Bosch ME 7.5 ECU is a very complicated system, which is torque based and makes decision based on input and feedback from all sensors needed to perform the stoichiometric calculations for optimum engine performance and torque. Failure of any of these components triggers its built-in the safety feature "limp mode" and lights up the EPC warning light. Unlike cable systems that can fray and get  stuck at high revs or high speed which often result in accidents,  "limp mode" deactivated torque and limits the revs to 1500 rpm yet allows the car to limp home safely. Many are asking, how to fix "limp mode"? The following cases are all different yet had the same symptoms - limp mode turning on the EPC warning light. The first is a Jetta, the second a Polo, the third a Seat Ibiza and the fourth a Skoda Fabia. See also  VW Polo highline, vw volkswagen limp mode,   limp home mode and  Audi limp mode.

FIRST CASE / VW LIMP MODE

Lately I've been having some issues with my Jetta 2.0T. She just suddenly went into "limp mode" or "safe mode" and it happened thrice during this week, resulting in total loss of power. I'm at my tether end, I have no idea what to do or how to rectify the situation. The first two times she went into "limp mode" the EPC warning light did not come on, however on the third occasion it came on and now stays on and  hasn't gone off since.  Initially I thought it was because the pump jockey threw-in LRP instead of unleaded fuel  but I have since rectified the situation and its not that.  I've run Vag-com diagnostics twice, which revealed the following data. I need help to repair this problem else I would have to take it to the service agents. Just the thought of a huge repair bill kept me from going there in the first place.

(First scan)
Control Module Part Number: 1K0 907 115 B
Component Version: 2.0l R4/4V TFSI 00 0010
1 Fault Found:
000818 - Knock Sensor 2 (G66): Signal too Low
P0332 - 002 - Lower Limit Exceeded - Intermittent

Freeze Frame:
Fault Status: 00100010
Fault Priority: 0
Fault Frequency: 2
Mileage: 18745 km
Time Indication: 0
Date: 2015.01.12
Time: 14:41:21

Freeze Frame:
RPM: 2555 /min
Load: 86.1 %
Speed: 52.0 km/h
Temperature: 77.0°C
Temperature: 39.0°C
Absolute Pres.: 1001.0 mbar
Voltage: 14.323 V
Readiness: 0000 0000

(second scan)
Address 01: Engine
Part No SW: 1K0 907 115 B HW: 1K0 907 115 B
Component: 2.0l R4/4V TFSI 00 0010

1 Fault Found:
000818 - Knock Sensor 2 (G66): Signal too Low
P0332 - 002 - Lower Limit Exceeded - Intermittent

Freeze Frame:
Fault Status: 10100010
Fault Priority: 0
Fault Frequency: 2
Mileage: 18992 km
Time Indication: 0
Date: 2015.01.15
Time: 12:05:11

Freeze Frame:
RPM: 2444 /min
Load: 57.1 %
Speed: 61.0 km/h
Temperature: 89.0°C
Temperature: 45.0°C
Absolute Pres.: 989.0 mbar
Voltage: 12.066 V
Readiness: 0000 0000

EXPLANATION
Our fellow VW owner is concerned with the different results of his two scans. So first and foremost let me assure him that there is nothing to worry about because the Readiness passes with flying colour. Readiness is the operational status of  the 8 emission functions, viz  the (1st nought) Exhaust Gas Recirculation - EGR, (2nd nought) Oxygen Sensor Heater, (3rd nought) Oxygen Sensor, (4th nought) Air Conditioning, (5th nought) Secondary Air Injection System, (6th nought) Evaporative Emissions System, (7th nought) Catalyst Heating and  (8th nought) Three Way Catalyst.  However, not all vehicles are fitted with all 8 system. If the system is absent, the report default to a 0 but  a 1 signifies a fault in the respective system. The RPM, load, Speed and Temperature above, are all relative to how long the engine has been running, the gradient of the road etc. The Absolute Pres of 989.0 mbar is lower in scan two  than the Absolute Pres. of 1001.0 mbar of scan one  because the battery is lower. The optimum battery voltage is 14.4V. Anyway, to get back to the "limp mode" issue at hand.  I am almost certain the cause of "limp mode" in this case is the Knock Sensor 2 (G66) because of Signal too Low - lower than expected by the ECU.  The mere fact that the ECU reports a low signal implies that the wiring from the knock sensor to the ECU is intact and that the actual fault could be the knock sensor or the ECU itself . It is highly unlikely that the ECU is at fault because they are fairly robust, which leaves us with the knock sensor. Knock Sensors are torqued to the engine block for flush contact so that it would pick up the maximum amount of vibration. Should the bolt securing the Knock Sensor come loose, the knock sensor would send a lower signal than expected. See previous blog  Knock Sensor issue. Since the ECU cannot protect the engine in the absence of knock sensor 2 it decided to enter into "limp mode" to safeguard the engine from possible damage it a knock developed or vibrations exceeded the prescribed limit.

_______________________________________________

SECOND CASE  / VW LIMP MODE

I have a 9N - VW Polo and my car's EPC warning light comes on when I rapidly accelerate when driving at slow speeds or when accelerating rapidly while driving a steady speed. When the EPC warning light comes on, the car goes into "limp mode" at that very moment then he check engine light comes on.  I’ve scanned the ECU with VAG-COM  and after spending hours under the bonnet looking for a possible cause, I still haven't found  anything and need help or any suggestions so I can fix this problem.

Address 01: Engine
Part No: 036 906 034 FJ
Component: MARELLI 4MV 4830
3 Faults Found:

17961 - Barometric / Manifold Pressure Signals
P1553 - 35-10 - Implausible Correlation - Intermittent

17912 - Intake Air System
P1504 - 35-10 - Leak Detected - Intermittent

17550 - Load Calculation Cross Check
P1142 - 35-10 - Lower Limit Exceeded - Intermittent

Readiness: 0000 0101

EXPLANATION

The fact that the Readiness failed (see explanation above) more than explains why you are having car trouble. Since the 6th nought is a 1, it says that your  Evaporative Emissions System (EVAP) is faulty. The 8th nought is also a 1, which says that your Three Way Catalyst is at faulty. However, in your case it appears that hardware upstream of the catalytic converter is causing  the readiness to fail. The problems are associated with  Leaks Detected in the Mass Air Flow (MAF) / Intake Air System / Barometric / EVAP system . Since the incorrect amount of air needed  for stoichiometric calculations is inadequate, the fuel is not completely burnup and as a result the catalytic converter detects unburnt fuel and flags an error. The units themselves may not be faulty but rather the wiring and connectors of these units or cracks or cuts in the rubber hoses.  Repairing these should take  priority  because OBD-II is designed to shut the car down if it fails readiness and there therefore the minimum emission standards. Since the fuel is under pressure and the rubber hoses could be leaking fuel, safe mode (limp mode) is initialised.

_______________________________________________

THIRD CASE  / VW LIMP MODE

What is limp mode? My 6L-Seat Ibiza can idle but not rev, I think it has gone into limp mode, please help before I set this cas alight. Please explain what is limp mode? And how to fix limp mode. Here is the VAG-COM scan of modules with faults,

Address 01 ----------------------------------------------
Controller: 038 906 019 NF
Component: 1,9l R4 EDC 0000SG 5839

2 Faults Found:
18043 - Powertrain Data Bus: Missing Message from A/C Controller
P1635 - 35-10 - - - Intermittent

18045 - Powertrain Data Bus: Missing Message from Electronic Load Controller
P1637 - 35-10 - - - Intermittent

Readiness: N/A

Address 03 ----------------------------------------------
Controller: 6Q0 907 379 S
Component: MABS 8.0 front H03 0001
Coding: 0000008
Shop #: WSC 06441
Note: Excessive Comm Errors

Address 08 ----------------------------------------------
Controller:
Note: Excessive Comm Errors

EXPLANATION
For an explanation of what limp mode is, read the above. The two engine faults signify there could be a problem with the Data bus Wiring since neither the Electronic Load Controller nor the A/C Controller can send and receive messages. Coupled to the fact that Address 3 - ABS braking system  and Address 8 -Auto HVAC both have Excessive Comm Errors, further verifies trouble with the  Data bus. However it is more likely Fuses and /or Connector(s) from / to Central Electronics Control and the Gateway controller. The fact that the ECU cannot coordinate torque and braking it was best to shut the systems down and enter into safe mode (limp mode) since malfunction of these important systems may lead to an accident and for the very least make for a poor driving experience.

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FOURTH CASE  / VW LIMP MODE

I have a Skoda Fabia and I think there is problems with the butterfly of my throttle body or perhaps it is dirty because the car goes into "limp mode" continually.  I have given up on kickdown because  it is getting dangerous because whenever I want to overtake, my car goes into limp mode.   I would appreciate your commentary and your recommendations because  "limp mode" frustrates me and I curse all the time. Do you think the sensors are causing all my problems? Here is my Vag-com scan.

Address 01: ----------------------------------------------
Engine
Part No: 036 906 034 BL
Component:  MARELLI 4LV       3699
Coding: 00071
 
No fault code found.
Readiness: 1110 0101

Address 08: ----------------------------------------------
Auto HVAC      
Part No: 6Y0 820 045
Component: Klimaanlage        X0760

1 Fault Found:
00818 - Sensor for Evaporator Outlet Temperature (G263)
30-00 - Open or Short to Plus

Address 09: ----------------------------------------------

Cent. Elect.  
Part No: 6Q1 937 049
Component: BORDNETZ-SG.1S30

3 Faults Found:
00906 - Horn (H1)
28-10 - Short to Plus - Intermittent

00778 - Steering Angle Sensor (G85)
49-00 - No Communications

01324 - Control Module for All Wheel Drive (J492)
49-00 - No Communications

Address 15: ----------------------------------------------
Airbags    
Part No: 1C0 909 601 C
Component: 02 AIRBAG VW51 01
 
1 Fault Found:
00532 - Supply Voltage B+
07-10 - Signal too Low - Intermittent

Address 19: ----------------------------------------------
CAN Gateway
Part No: 6N0 909 901
Component: Gateway K<->CAN 1S30
 
2 Faults Found:
00778 - Steering Angle Sensor (G85)
49-00 - No Communications

01324 - Control Module for All Wheel Drive (J492)
49-00 - No Communications

Address 44: ----------------------------------------------
Steering Assist  
Control Module Part Number: 6Q0 423 156 AB
Component and/or Version: LenkhilfeTRW        V270
Software Coding: 10140
1 Fault Found:

00816 - Power Steering Sensor (G250)
30-10 - Open or Short to Plus - Intermittent

EXPLANATION
This Skoda Fabia seems to have enough problems for half a dozen cars. Once again we need to look at Readiness first because it is quite evident that there more 1's than 0's. That tells us there are problems  in the (1st nought) Exhaust Gas Recirculation - EGR, (2nd nought) Oxygen Sensor Heater, (3rd nought) Oxygen Sensor,   (6th nought) Evaporative Emissions System  and  (8th nought) Three Way Catalyst. This is reason enough for the car to go into limp mode. But since it also has issues with its  Steering Angle Sensor (G85)
and the Control Module for All Wheel Drive (J492) there is even more reason to shut the important systemes down and do into safe mode (limp mode). There are also several electrical issues with open circuits and short circuits which would most likely be wiring harness related. But the most striking thing is the  Low - Intermittent  Supply Voltage B+ which implies the battery terminal is loose. Intermittent supply voltage  resets all modules all the time and can lead to spurious DTC.

EPC NIGHTMARE

EPC WARNING LIGHT

Over the past 3 years I have had some  13775 EPC information requests. That's roughly 4500 request per year, each and everyone of  them EPC related.  I manages to help several Vag car owners with their EPC problems however many were unable to give me the  DTC codes that could be causing the EPC problems. So, If you have a scan of your car feel free to upload it to my blog, I will analyse it and post the answer for everyones benefit.  I have found that the commonest EPC problem is the accelerator pedal potentiometers. However they cannot be purchased as a separate item. You have to buy the complete accelerator pedal. There is a plug that is attached to  the accelerator pedal, the plastic bit where the yellow stickers are, contains the pots.  If you are having EPC problems you are not alone. Read some of your fellow Vag car owners woes.

NO EPC DTC CODES

What is EPC on a Volkswagen? My car loses power all the time. If  I turn the car off and leave it for a while,  the problem goes away. This happened to be a couple of months ago, and  I was forced to take  it to a VW dealer.  They had no idea what to do. The car idles  really badly and the EPC light is on from the moment I start it,  besides now the check engine light is also on. I'm  thinking about replacing the throttle body but it cost about is $600. That's crazy man.

TOO VAGUE & NO EPC DTC CODES

My EPC light came on and car lost all power, so now I am having the most weirdest problems. I got stuck on the freeway, my EPC light came on and I had to pull onto the shoulder of the road because I lost acceleration. Disconnected and reconnected the negative battery terminal to reset the system, then she was driving fine. Took it to VW guy but he has no idea what an EPC problem is or at least he wanted me to  pay him  first before would help. He wants $85 an hour.

NO EPC DTC CODES, CAN'T ASSIST

I have an  VW Polo 1.4 and the 'Check Engine light' and EPC warning light  blinks for the past few months. Replaced the throttle body and potentiometer  and wiring to the engine manifold were replaced.  The same problem still persists and car  will stall at random causing these warning lights and EPC to switch on.

NO EPC DTC CODES, NO HELP

My polo 1.2  epc light comes on when I stop at traffic lights and goes into limp mode then can only drive  15 mph max without   pressing the accelerator. Took  it to a service agents who condemned  the throttle body, so had it replaced. The EPC light still comes on.

Feel free to upload your VW, SKODA, SEAT & AUDI scans.

EPC DEMYSTIFIED CONTINUED 2

Continued from EPC DEMYSTIFIED CONTINUED 1.

  ...  I only became aware of this when my EPC light went on due to the knock sensor. See picture blog.  More...

 PART 3

BREAKING THE CODE

What needs to be mentioned as a basis of understanding, is that OBD (on-Board Diagnostics) was introduced in the 70's along with CDI (capacitive discharge ignition systems) as DIY kits. Few cars had fuel injectors, points and coils were fast being taken over by electronic modules. During this time some standards were introduced but they were not very well defined and as such manufacturers developed their own and applied their specific systems and developed their own code descriptions which later became known as OBD1. This was considered undesirable and counterproductive since none franchised service, and general mechanical repair centers had to purchase different scan tools, interface cables and connectors, skills and manuals for each make and model of car they specialized in. This resulted in vehicle diagnostics becoming unwieldy expensive. In February of 1986, Robert Bosch founder of Bosch, introduced the CAN (Controller Area Network) serial bus system to  the Society of Automotive  Engineers (SAE) in motor town of Detroit.

This influenced the  Society of Automotive  Engineers (SAE) who subsequently drafted a list of standards and practices that aught to be implemented by all automobile  manufacturers and recommended them to the Environmental Protection Agency (EPA). The EPA weighed-up these standards and recommendations, acknowledged their benefits, and adopted them. The standards criteria included a precisely defined diagnostic connector for each auto manufacturer, a standard scan tool and a common electrical communications protocol and a common data format, and the ability to monitor other
vehicle parameters. Lastly that the standard scan tool should interface with vehicles of all manufacturer. It also included mandatory definitions and descriptions for certain emission control system  defects which was labeled the ‘P0’ Codes. Manufacturers were allowed to generate and use their own ‘manufacturer specific code descriptions’ known as ‘P1’ Codes. This collaboration of standards became known as OBDII, (OBD2) and was adopted for implementation by January of 1996. Two types of scanner codes, namely manufacturers codes like VAG codes and SEA Codes are now the standard practice.

OBD-II  

As mentioned above, Powertrain Control Module (PCM) error codes are assigned the prefix P and pertain to the, Engine management, Transmission management, Fuel Pump and Gasoline Management, Automatic Transmission – Hydraulic Control, Emission control system, evaporative emission purge control (HVAC), Auxiliary module management and other some 0n-board Hybrid application.  For example P1340  suggests that the Powertrain triggered a DTC and describes it as an "Crankshaft-/Camshaft Position Sensor Signals Out of Sequence"

From the above example it would thus be easy to interpret the DTC below relating to EPC (Electronic Power Control)

DTC (VAG)   DTC (SAE)  Society of Automotive  Engineers

16504 P0120 Throttle Position Sensor A - Circuit Malfunction
16505 P0121 Throttle Position Sensor A - Circuit - Performance Problem - Out of Range
16506 P0122 Throttle Position Sensor A Circuit - Low Voltage Input
16507 P0123 Throttle Position Sensor A Circuit - High Voltage Input
16894 P0510 Throttle Position Sensor - Closed Switch- idle micro-switches -F60 malfunctioning
17951 P1543 Throttle Actuation Potentiometer - Signal too Low
17952 P1544 Throttle Actuation Potentiometer - Signal too High
17913 P1505 Throttle idle micro-switches -F60 not/short-circuit opens
17914 P1506 Throttle idle micro-switches - Switch Does Not Open/Short to Ground
17988 P1580 Throttle Actuator (B1) Fault - May be caused by low battery if found with 16487 (P0103)

18038 P1630 Accelerator Pedal Position -G79 signal too small  (low)
18039 P1631 Accelerator Pedal Position -G79 signal too largely (high)
18040 P1632 Accelerator Pedal Position -G79 supply voltage malfunction
18041 P1633 Accelerator Pedal Position -G185 signal too small
18042 P1634 Accelerator Pedal Position -G185 signal too largely
18047 P1639 Accelerator Pedal Position 1+2 Range/Performance -G79 and -G185 implausible signal
18048 P1640 Internal Controller Module defective (EEPROM) Error

EPC Circuit.

The EPC  circuit consists of a number of disparate components that control and supervise, regulate and determine the throttle valve position at all times. They include;

1) the accelerator pedal position sender (TP sensor G69)
2) the accelerator pedal position sender -2, (G185)
3) Black 6-pin plug with 6-pin with Gold plated contacts

NB! The above three components are part of the accelerator pedal.

4) the throttle valve control module (unit),
5) the K132 EPC fault lamp, (electronic throttle control fault indicator)
6) the engine control module (unit).

Firstly we going to do a test on components 1, 2 and 3 above. To do this test, you need a Fluke multimeter or similar for a voltage and continuity / resistance test. Unplug the 6-pin plug from the accelerator pedal and switch on the ignition. Connect the multimeter and check for a 4.5 volt reading between;-

pin 1 and ground, then between pin 1 and pin 5
Pin 2 and ground, then between pin 2 and 3.
If tests prove to be "OK", switch ignition off.
Do additional checks for short circuits between one another and ground and if this checks "OK",

Locate the ECU, normally inside cowl. Disconnect the ECU from its socket, identify pins 34 & 34, 35 & 36, and 72 & 73 on the socket. Disconnect the 6-pin plug from the accelerator pedal once again and check for continuity between this plug and the ECU socket. There should be continuity between pins:-

1 of the 6-pin plug and pin 72 of the ECU socket.
2 of the 6-pin plug and pin 73 of the ECU socket.
3 of the 6-pin plug and pin 36 of the ECU socket.
4 of the 6-pin plug and pin 35 of the ECU socket.
5 of the 6-pin plug and pin 33 of the ECU socket.
6 of the 6-pin plug and pin 34 of the ECU socket.

Any resistance above 1.5ohms should be investigated for corrosion. This often causes the engine to surge (idle unevenly or rather breaths) However, if this test proves "OK" and no wiring malfunction is detected, replace G69 and G185 (single unit) on the accelerator pedal. NB! these components are non adjustable and needs to be replaced as a whole.

When the ignition is turned on, the ECU checks all EPC components necessary for the proper  functioning of the Electronic Power Control. If a malfunction is detected in the EPC (Electronic Power Control) system whilst the engine is running, the ECM will simultaneously activate the EPC (Electronic Power Control) warning light and make an entry of this malfunction in  the ECU (electronic Control unit) DTC (Diagnostic Trouble Codes non-volatile memory.  By a process of eliminate the EPC fault can be fixed.

The list below categorises VW and Audi manufacturer predetermined data groups which varies depending on the vehicle, year, engine, engine code and management system on board.

Group Number / Group Category

1–9     General engine activity data
10–19 Ignition data
20–29 Knock control data
30–39 02 sensor control system data
40–49 Three-way CAT data
50–59 Engine speed control data
60–69 Throttle drive data
70–79 Emissions reduction data
80–89 Special function data
90–97 Power increase data
98–100 Compatibility data
101–109 Fuel Ignition data
110–119 Boost pressure control data
120–129 Control unit communication data
130–150 Special info data

Based on the data from the above table EPC problems are associated with group 60-69. However, on Expert Systems Diagnostics Group 60, holds the EPC Adaptation data, group 61 holds EPC-system 1 data and group 62 holds the EPC system 2 data. Group 66 holds the speed-o-cruise data.

NB! If you found this information useful, please link to this page.

EPC DEMYSTIFIED CONTINUED 1

Continued from EPC DEMYSTIFIED.  

  ....But it’s not that simple. There is a lot more to it than meets the eye.....

 PART 2

But it’s not that simple. There is a lot more to it than meets the eye. Cars exclusively use embedded microcontrollers (µContollers) with embedded firmware in preference to microprocessors with loadable software. In order for a microprocessor to function properly in any device, it must contain dedicated internal circuitry and firmware specific to its function, have inputs and outputs and an oscillator circuit among other circuitry and an OS (Operating system). A DVR (Digital Video recorder), or a PVR (personal Video recorder) or a set-top-box or embedded network appliance or data router are just a few examples of such systems. µControllers  are less significant and less sophisticated than microprocessors, more dedicated to its specific need, often cheaper, faster, safer and smaller. Embedded µControllers are therefore the natural choice for car manufacturers. And there are several manufactures that produce µControllers families specifically for the motor trade.

So it should be understood that companies like Bosch, Digifant, Delco  and other engine management ECU manufacturers and electronic module manufacturers uses the same microcontroller chip families or similar microcontroller chip families, designed and manufactured for them by a selected few silicon chip manufacturers.  In the same vein, computer manufacturers like IBM, Dell, Sony, Toshiba and Lenovo, etc. all use microprocessors manufactured by Intel Corporation or AMD in their laptops and computers, whereas Apple uses microprocessors manufactured by Motorola.

Baring in mind, that much like Motorola, Intel Corporation and AMD produces different featured microprocessor chips with different instruction sets,  along with their auxiliary support chips for low-end and high-end computers; such as 4 bit, 8bit, 16bit, 8086 family of chips, 32bit Pentiums, I5, I7, 64bit, XEON, 128bit big Endian and small Endian microprocessors etc; so does Infineon, Altera, Freescale, Atmel and ARM etc, manufacture different featured microcontroller chips for both low-end cars and high-end cars which are specifically chosen for their internal features and software by the various ECU and electronic module manufacturers like  Bosch,  LUCAS, DENSO, Delco, DELPHI, FENIX, HITACHI, HELLA,  MARELLI, Siemens, etc. These microcontroller chip families can roughly be categorized into four sub sectors, those specific to Powertrain functions (P), those specific to the Body and Safety functions (B), those with specific functions for Chassis (C) and those specific to Internal Convenience & communication(U).

In a nutshell all the sub systems in your vehicle are controlled by these on-board computer chips, each at the heart of an electronic module flanked by associated components and sensors. Each of these modules are in fact a fully fledged computer in its own right, situated in various positions throughout the car and linked together by a wired networked called a network bus and all are accessible through the Databus diagnostic interface for adaptation.

When the ignition is switched on, several dashboard warning lamps light-up and stays lit for the duration of the internal test cycle (<30 seconds). Should all tests check OK, all lights goes however if all systems does not check out OK, the relevant light will stay on and a fault will be logged in memory . After the car is started, the ECU monitors all sensors  and continually takes readings from the complete range of powertrain modules and sensors. These readings are then compared with default readings stored in the operational logic of the  system. Should the sensor reading coincide and agree with the stored program value or values, the microcontroller will send the  required outputs to the relevant actuators, for example the injectors. If the sensor readings differ and are out of specification,   "not within the required limits",  it will take another and if this sensor reading continues to be ‘out of limits’ a DTC will be triggered and sent to non-volatile memory. Depending on the nature of the fault, the embedded program may or may not instruct the microcontroller to make internal changes, thus operate on different criteria until a repair is effected, or until the fault has been cleared.

So whenever a mechanical or electronic problem arises in either the Powertrain (P), the Body (B), the Chassis (C) or the internal Conveniences & Communication (U) areas, the relevant module or modules triggers the on-board self diagnostics program and generates a DTC (Diagnostic Trouble Code) which is then stored in the non-volatile memory of the ECU for later retrieval by mechanical technicians. At the point When a DTC code is logged in memory, the system self-diagnosis system also alerts the driver with a visible indication  of trouble by turning on a warning light on the dashboard like the "EPC light", or the "Malfunction Indicator Lamp" (MIL) which on European cars is known as the "Check Engine Light". This doesn't tell you  the nature of the problem, even though it could be something serious, or not. After the necessary repairs are completed, a diagnostic scan tool should be used to clear the DTC errors  and to turn the malfunction indicator light (MIL) or EPC light off. Thereafter the car should be taken on a short test dive to ascertain that the previous drive issue or issues are resolved. Then the car should be hooked up to the diagnostic scan tool once again in order  to confirms that the DTC or DTCs is also no longer present.

The nature of such mechanical problem may  prevent the engine from starting or it may idle erratically, switch off immediately after starting, refuse to rev higher than 1500 rpm and impede driveability (limp mode), difficult cold starting, misfire, lazy acceleration, high idling speed, fluctuating rev counter, excessive fuel consumption, difficult warm starting, excessive black smoke, poor engine response or emits blue/grey smoke,  etc ... Each of these faults and so many others each produce individualized codes.   In most cases it would be expedient to engage the services of a roll-back to get your car to a VW service center so that diagnostics can be run on the car.

With sufficient knowledge and an appropriate diagnostic apparatus (Autoboss, Pico Scope, Range, VCDS, AutoEnginuity,  ScanXLpro), code reader or scanner, plugged into the car's 16 pin diagnostic plug, mechanical minded persons can read these faults, print then or save them to an SD card or harddrive, send signals and communicate with the ECUs, read the measured values and interrogate the actuators. The DTC in memory however do not identify the part that has gone faulty but rather provides you  with a general idea to its area of origin. Often long before a DTC code is generated the fault may already have existed so when the you view the DTC it could show that the fault occurred twice of thrice or even six times before. The ECU software is designed to monitor the frequency of error and if it is an isolated occurrence the ECU clears the fault after a certain distance is traveled but that dependent on the severity of the fault. For arguement's sake lets say 300kms. If it happens once in 300kms it could automatically clears the fault but should it happen four times during the same distance a DTC will be registered, the car could go into limp mode since it may be unsafe to drive the car if it's a breaking or steering issue, or shut the engine off if the O2 sensor went faulty and can't regulate the smoke pollution, or disable starting if the knock sensor triggered the DTC as there may be no oil in sump which could amount to a very expensive engine repair. In the case of the latter, the oil light should have illuminated long before the knock sensor shuts the engine off. However I have encountered a problem with the wires that plug into the oil sensor that became brittle due to engine heat and  subsequently broke off. As a result the sender  sent the low oil condition but it never arrived at the the ECU hence did not turn-on the oil-low light. I only became aware of this when my EPC light went on due to the knock sensor. See picture in blog.   More ...